1. Field of the Invention
The invention relates to an electroacoustic transducer comprising a voice coil and further comprising a diaphragm which is intended for cooperation with an air mass in an acoustic free space situated in front of the diaphragm and which can be set into vibration by means of the voice coil substantially parallel to a direction of vibration. The diaphragm has an annular outer zone, end a central zone which is convex with respect to the acoustic free space situated in front of the diaphragm, and a peripheral zone which diverges towards the acoustic free space in front of the diaphragm. The peripheral zone is connected to the central zone by an annular intermediate zone and terminates in the outer zone of the diaphragm, the annular intermediate zone being constructed for securing the voice coil of the transducer to the diaphragm.
The invention further relates to a diaphragm for an electroacoustic transducer, which diaphragm is intended for cooperation with an air mass in an acoustic free space situated in front of the diaphragm, and which can be set into vibration by means of a voice coil substantially parallel to a direction of vibration. The diaphragm has an annular outer zone a central zone which is convex with respect to the acoustic free space situated in front of the diaphragm, and a peripheral zone which diverges towards the acoustic free space in front of the diaphragm. The peripheral zone is connected to the central zone by an annular intermediate zone and terminates in the outer zone of the diaphragm, the annular intermediate zone of the diaphragm being constructed for securing the voice coil of the transducer to the diaphragm.
2. Description of the Related Art
An electroacoustic transducer of the type defined in the first paragraph and a diaphragm of the type defined in the second paragraph are known, for example, from the document U.S. Pat. No. 5,303,209. It is to be noted that a known transducer of the type defined in the first paragraph is commercially available from the Applicant in several versions, for example, under the type number WD 02901/Y50L. In the known transducer, the convex central zone is spherical and the diverging peripheral zone has a flared shape corresponding to a part of a torus. In the known transducer, the annular intermediate zone, which serves as a mounting zone for securing the voice coil of the transducer to the diaphragm, takes the form of an annular disc, a plane through this annular disc extending perpendicularly to the transducer axis. Due to this shape of the intermediate zone in the known transducer, this intermediate zone is situated comparatively far away from the magnet system of the known transducer, as a result of which the voice coil must be comparatively high in order to extend into the air gap of the magnet system. This, in turn, results in the voice coil being comparatively heavy, which is unfavorable for a maximal sensitivity--i.e., for a maximal conversion factor between the applied electric power and the delivered sound pressure--and which also makes the voice coil more expensive, because the voice coil should have a comparatively large number of turns in order to obtain the required height. Moreover, as a result of the comparatively high voice coil, the position of the voice coil with respect to the air gap of the magnet system exhibits a comparatively high degree of asymmetry, which leads to a comparatively large amount of non-linear distortion in the known transducer.